DNA video project DNA video project SOME BACKGROUND INFO…SOME BACKGROUND INFO…

WHAT IS THE “STUFF” OF HEREDITY?WHAT IS THE “STUFF” OF HEREDITY?WHAT IS ITS STRUCTURE?WHAT IS ITS STRUCTURE?

The following scientists helped to The following scientists helped to answer these questions.answer these questions.

GriffithGriffithAveryAveryHershey-ChaseHershey-ChaseWatson, Crick Watson, Crick Wilkins and FranklinWilkins and FranklinChargaffChargaff

I. GRIFFITH’S EXPERIMENT 1928I. GRIFFITH’S EXPERIMENT 1928A.A. - - make a vaccine againstmake a vaccine against harmful S. harmful S. pneumoniae pneumoniae bacteriabacteria 1. 1. virulent S strainvirulent S strain ( (S. pneumoniaeS. pneumoniae)) a. virulent means disease causinga. virulent means disease causing b. capsule around the bacteria b. capsule around the bacteria provides protection from body provides protection from body defensesdefenses 2. 2. non virulent Rnon virulent R strainstrain (no capsule) (no capsule) a. destroyed by body(can not causea. destroyed by body(can not cause disease)disease)

B.B. PROCEDURE and RESULTS PROCEDURE and RESULTS

1. mouse injected with R 1. mouse injected with R cellscells

2. mouse injected with S 2. mouse injected with S cells cells

3. mouse injected with 3. mouse injected with heat killed S cells heat killed S cells

4. mouse injected with 4. mouse injected with killed S cells mixed killed S cells mixed with live R cellswith live R cells

mouse livesmouse lives

mouse diesmouse dies

mouse livesmouse lives

mouse diesmouse dies

Results of Griffith’s ExperimentResults of Griffith’s Experiment

C.C. C C - Heat-killed S bacteria release - Heat-killed S bacteria release hereditary material that makes R strain hereditary material that makes R strain bacteria virulentbacteria virulent

HOW???HOW???

1.1.Principle of TransformationPrinciple of Transformation

a. transfer of genetic material (DNA) a. transfer of genetic material (DNA) from one organism to another from one organism to another

b. DNA for making a capsule was b. DNA for making a capsule was transferred from the S strain to thetransferred from the S strain to the

R strain making it virulentR strain making it virulent

II. II. AVERY’S EXPERIMENTS (early 1940’s)AVERY’S EXPERIMENTS (early 1940’s)

AA – Is the transforming agent protein, – Is the transforming agent protein, RNA or DNA?RNA or DNA?

BB. . PROCEDUREPROCEDURE – (Three Experiments)– (Three Experiments)

1. destroy 3 different molecules in the 1. destroy 3 different molecules in the

heat-killed S strain bacteria and mix heat-killed S strain bacteria and mix

with R strain bacteriawith R strain bacteria

a. destroy a. destroy proteinprotein (protease enzyme) (protease enzyme)

b. destroy b. destroy RNARNA (RNase enzyme) (RNase enzyme)

c. destroy c. destroy DNADNA (DNase enzyme) (DNase enzyme)

C. ResultsC. Results1. Missing protein1. Missing protein a. transforms R cells to S cellsa. transforms R cells to S cells (mouse dies)(mouse dies)

2. Missing RNA2. Missing RNA a. transforms R cells to S cells)a. transforms R cells to S cells) (mouse dies)(mouse dies)

3. Missing DNA3. Missing DNA a. did not transform R cells to S cellsa. did not transform R cells to S cells (mouse lives)(mouse lives)

Oswald AveryOswald Avery

D. Conclusion D. Conclusion – DNA is responsible for– DNA is responsible for

the transforming principlethe transforming principle

III. HERSHEY-CHASE EXPERIMENTIII. HERSHEY-CHASE EXPERIMENT1952 (Martha Chase and Alfred Hershey)1952 (Martha Chase and Alfred Hershey)

– – Is the hereditary material in viruses protein or Is the hereditary material in viruses protein or DNA? DNA?

B.B. PROCEDURE PROCEDURE 1. Label protein and DNA in a phage with 1. Label protein and DNA in a phage with

radioactive isotopes (S-35 and P-32)radioactive isotopes (S-35 and P-32)

a. a phage is a virus that attacks a. a phage is a virus that attacks bacteriabacteria b. S-35 labels protein and P-32 b. S-35 labels protein and P-32 labels DNAlabels DNA

Martha Chase and Alfred Hershey usedMartha Chase and Alfred Hershey usedPhage Viruses for Their ExperimentPhage Viruses for Their Experiment

B. ProcedureB. Procedure

2. Allow protein-labeled and DNA-2. Allow protein-labeled and DNA- labeled phage (virus) to infect labeled phage (virus) to infect E. coliE. coli bacteriabacteria 3. remove and separate phage (virus)3. remove and separate phage (virus) from the bacteria (from the bacteria (E. coliE. coli))

Hershey-Chase ExperimentHershey-Chase Experiment

- all viral DNA and a small amount of protein entered the all viral DNA and a small amount of protein entered the bacteriabacteria

D.D. CONCLUSIONCONCLUSION - - DNA is the hereditary molecule in viruses DNA is the hereditary molecule in viruses

IV. Watson and Crick (1953) /Wilkins and IV. Watson and Crick (1953) /Wilkins and FranklinFranklin

A. Watson and CrickA. Watson and Crick 1. double helix model of DNA based on the1. double helix model of DNA based on the work of other scientistswork of other scientistsB. Maurice Wilkins and Rosalind FranklinB. Maurice Wilkins and Rosalind Franklin 1. x-ray diffraction photographs of DNA 1. x-ray diffraction photographs of DNA helped Watson and Crick develop their helped Watson and Crick develop their modelmodel 2. Watson, Crick and Wilkins received 2. Watson, Crick and Wilkins received Nobel Prize in l962 (Franklin died in 1958Nobel Prize in l962 (Franklin died in 1958 and could not be named for the award)and could not be named for the award)

X-ray Diffraction Photo Rosalind FranklinX-ray Diffraction Photo Rosalind Franklinof DNA) and Maurice Wilkensof DNA) and Maurice Wilkens

DNA Double Helix Watson and CrickDNA Double Helix Watson and Crick

V. Erwin Chargaff - 1949V. Erwin Chargaff - 1949

A. Percent of nitrogen bases that pair with A. Percent of nitrogen bases that pair with each other (each other (complementary basescomplementary bases) is the ) is the samesame

1. percent1. percent adenineadenine equals percent equals percent thyminethymine

percent percent guanineguanine equals percent equals percent cytosinecytosine

2. implied 2. implied base pairing rulesbase pairing rules

IV.DNA

(Structure / Function)

Questions you should be able to answer…

1) Where is DNA located in the cell?2) How is it arranged?3) What is the purpose of DNA? What does it

do????4) How many strands does it have and what

does it generally look like?5) What is the basic building block of DNA

called and what three components make it up?

6) What are the complimentary base pairs of DNA?

Chromosome - DNAChromosome - DNA Chromosome-ChromatidChromosome-Chromatid

Where is it located in the cell? NUCLEUS! How is it arranged?

Purpose? To code for everything in your body...genetic blueprint!

DNA Structure

1. Deoxyribonucleic acid is shaped like a twisted ladder (double helix)

2. DNA is a polymer made up of monomers called nucleotides

Each nucleotide consists of: a. a sugar called

deoxyribose

b. a phosphate

c. 1 of 4 nitrogen bases(A, G, T, C)

DNA Structure

Purine and pyrimidine

• adenine nitrogen bases (purine)= thymine nitrogen bases (pyrimidine)

• guanine nitrogen bases (purine)= the cytosine nitrogen bases (pyrimidine)

DNA Structure

Erwin Chargaff: discovered complementary base pair rules

• the # of adenine nitrogen bases = the # of thymine nitrogen bases

• the # of guanine nitrogen bases = the # of cytosine nitrogen bases

DNA Structure

A = T

G= C

DNA carries the genetic code in its sequence of bases

What is the complementary sequence of the bases listed below?

A T T G C A A G C T C T G C

3. The sides of the DNA helix are held up by phosphates and sugars (deoxyribose)

Hydrogen bonds: hold complimentary basestogether; very weak and can be easily broken

DNA Structure

DNA Replication

Build a DNA molecule

http://learn.genetics.utah.edu/content/begin/dna/builddna/

WE ALSO HAVE RNA in our WE ALSO HAVE RNA in our bodiesbodies

A. RNA containsA. RNA contains 1. sugar molecule -1. sugar molecule - riboseribose 2. phosphate 2. phosphate 3. nitrogen bases 3. nitrogen bases a. a. adenineadenine and and guanineguanine bb. . cytosinecytosine and and uraciluracil B. The three types of RNA are:B. The three types of RNA are: a) a) messenger RNAmessenger RNA (m-RNA) (m-RNA) b) b) transfer RNAtransfer RNA (t-RNA) (t-RNA) c) c) ribosomal RNAribosomal RNA (r-RNA) (r-RNA)

Differences between DNA -RNADifferences between DNA -RNA

DNA RNADNA RNADeoxyribose RiboseDeoxyribose Ribose

Double strand Single strandDouble strand Single strand

Thyamine UracilThyamine Uracil

DNA vs RNADNA vs RNA

A = TG=

But it’s the DNA that carries the genetic code in its sequence of basesGENES are segments of DNA that code for characteristics!

C

GENES ARE SEGMENTS OF DNATHAT CODE FOR A CHARACTERISTIC, LIKE DIMPLES. REALLY ITS THE ORDER OF THE BASES IN THE DNA DETERMINE THE CHARACTERISTIC. BUT SOMETIMES PROBLEMS ARISE….

MutationsMutationsA. Location of MutationsA. Location of Mutations 1. 1. somatic cellsomatic cell (body cell) (body cell) 2. 2. germ cellgerm cell (cells that form sperm (cells that form sperm and egg cells)and egg cells)B. CausesB. Causes 1. radiation 1. radiation a. x-rays, alpha, beta, gamma a. x-rays, alpha, beta, gamma radiation, u.v. lightradiation, u.v. light 2. chemicals (2. chemicals (mutagensmutagens)) 3. DNA sequence changes in replication 3. DNA sequence changes in replication

C. Effects of MutationsC. Effects of Mutations

1. 1. lethallethal (deadly) (deadly)

2. may be beneficial2. may be beneficial

3. no effect3. no effect

Point MutationPoint Mutation

change in one nucleotide …or change in a change in one nucleotide …or change in a basebase (A,T,C,G) in the DNA molecule (A,T,C,G) in the DNA molecule

Types of mutations –

a. substitution – one base is substituted for another b. addition or insertion – an

extra base is added c. removal or deletion of a

base

Point Mutation:Point Mutation:Substitution of One BaseSubstitution of One Base